☰
Is Matter Around Us Pure
By how much does the momentum of a body of mass 5 kg change when its speed
(i) decreases from 20 m/s to 0.20 m/s; and
(ii) increases from 30 m/s to 40 m/s?
(i) Here,
Mass of the body, m = 5 kg
Initial velocity, u = 20 m/s
Final velocity, v = 0.20 m/s
Change in momentum = m(v - u)
= 5(0.20 - 20) kg m/s
= -99 kg m/s
The negative sign shows that the momentum decreases.
(ii) Here,
Mass, m = 5 kg
Initial velocity, u = 30 m/s
Final velocity, v = 40 m/s
Change in momentum = m(v - u)
=5(40-30)
= 50 kg m/s
Here, the momentum of the body decreases, when it's speed increases.
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Which separation techniques will you apply for the separation of the following?
Different pigments from an extract of flower petals.
Which separation techniques will you apply for the separation of the following?
Butter from curd.
Write the steps you would use for making tea. Use the words—solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.
Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).
|
Substance Dissolved |
Temperature in K |
||||
|
283 |
293 |
313 |
333 |
353 |
|
|
Potassium nitrate |
21 |
32 |
62 |
106 |
107 |
|
Sodium chloride |
36 |
36 |
36 |
37 |
37 |
|
Potassium chloride |
35 |
35 |
40 |
46 |
54 |
|
Ammonium chloride |
24 |
37 |
41 |
55 |
66 |
Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.
|
Substance Dissolved |
Temperature in K |
||||
|
283 |
293 |
313 |
333 |
353 |
|
|
Potassium nitrate |
21 |
32 |
62 |
106 |
107 |
|
Sodium chloride |
36 |
36 |
36 |
37 |
37 |
|
Potassium chloride |
35 |
35 |
40 |
46 |
54 |
|
Ammonium chloride |
24 |
37 |
41 |
55 |
66 |
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